Ultrasonic based structural damage detection using combined finite element and model Lamb wave propagation parameters in composite materials

This paper presents a combined finite element and model Lamb waves propagation parameters method as a tool for structural health monitoring in composite materials. Modal analysis allows identifying the mode conversions induced by the defects. A simulation combining a lossless finite element approach and Lamb wave propagation parameter for finding natural frequencies and mode shapes of the structures in undamaged and damaged condition is proposed. This analysis is performed on two carbon-fiber-reinforced plastic bars in both undamaged and damaged state, where the two damaged states are (1) having a cut partway through the bar, perpendicular to the long axis of the bar and (2) having a circular hole. The lamb wave propagation parameters are calibrated using the ultrasonic pulse generator test setup. The natural frequencies for the theoretical, finite element and experimental results are compared and close agreement is found between the frequencies obtained experimentally and computationally.